“Open Design” guarantees a transparent and open process for planning and designing the software. It’s about letting go of the control of the design of the software and its feature road-map, and accepting that it should be driven by the community.
This is not easy to do. Design is an opinionated process. Design by committee can be inefficient. It’s easier and faster to keep design and feature development in the hands of a happy few, behind closed doors, than it is to get consensus across a community around desired features and priorities. But that would be choosing to go fast in the short term with a small group rather than going far in the long term with a larger group. Community-agreed design will lead to a better product that better answers the need of the users.